AVS 56th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP1
Extension of Aluminum Etch using a Carbon Mask for High Aspect Ratio 70nm Al Etch with a Chlorine Based Chemistry

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Plasma Science and Technology Poster Session
Presenter: G. Ding, Applied Materials, Inc
Authors: G. Ding, Applied Materials, Inc
B. Schwarz, Applied Materials, Inc
C. Lee, Applied Materials, Inc
Correspondent: Click to Email
A strippable amorphous carbon hardmask has many advantages over traditional resist or oxide hard masks, it is widely used in frond end applications. However carbon masks for Al etch in backend applications has not been employed. The final CD as well as the aspect ratio that can be achieved with a carbon based mask for Al etching, and how that mask would benefit over traditional PR masks and oxide hard mask are discussed. In this study, we focused on non-fluorine or low-fluorine containing chemistries to achieve a high mean wafers between clean (MWBC) performance. The selectivity/budge for the film stacks (PR => SiON => carbon film =>Al etching) using this approach are illustrated. The carbon mask has shown to achieve less than half of final CD while doubling the mask selectivity over than those best achieved in the PR mask. CD uniformity of 5 nm (3sigma) uniformity was achieved. We demonstrate a wide range of CD tunability (± 20 nm). Throughput and throughput optimization is discussed. The different passivation mechanisms for different masks, PR mask, Oxide hard mask and carbon mask in Al etch are discussed. We demonstrated similar trends between resist and carbon and baseline what leads to excellent transferability of the etch process. This study shows the significant process benefit of the carbon-Al etch in comparison to the oxide HM and PR mask, which will allow Aluminum etch to be continued from an etch perspective to sub 50nm lines with 6:1 aspect ratio.